What this code means
P0793 generally means the PCM may not be receiving the expected speed signal from the CVT drive pulley speed sensor circuit.
What the vehicle may do
- The vehicle may set a warning light.
- CVT operation may feel abnormal or limited.
- The fault can be intermittent or repeatable depending on the circuit condition.
Possible fault areas
- Possible sensor signal circuit issue.
- Possible sensor power or ground-reference issue.
- Possible connector or terminal problem between the sensor and PCM.
- Possible PCM software or PCM-related issue.
Diagnostic path
Opening context
On this Accord, P0793 is an intermediate shaft speed sensor A circuit no-signal code. In plain terms, the PCM may not be seeing the speed signal it expects from the CVT drive pulley speed sensor circuit. The vehicle may set a warning light, CVT operation may feel abnormal or limited, and the fault can be intermittent or repeatable. The broad fault areas are possible sensor power, sensor ground reference, signal-wire, connector, PCM software, or PCM-related issues. One important point: this diagnostic path treats P0793 as an electrical circuit problem, not a mechanical failure inside the transmission. Before getting deep into the circuit, start with the basic system checks and follow a structured diagnostic approach.
Verify the failure first
Start by verifying the problem. Turn the vehicle to the ON mode and clear the code with the HDS. Raise the vehicle on a lift, make sure it is securely supported, and make sure all four wheels can rotate freely. Start the engine, then disable VSA with the VSA OFF button. If vehicle speed is above 31 mph (50 km/h), use VSA maintenance mode. Test-drive it in D position or D mode, keep the vehicle at speeds over 19 mph (30 km/h) for at least 30 seconds, then slow down and stop the wheels. Now check for pending or confirmed codes with the HDS. If P0793 comes back, the failure is duplicated and you move into the circuit checks. If it does not come back, treat it as intermittent at this time. Check for poor connections or loose terminals between the PCM and the CVT drive pulley speed sensor, and if captured operating data is available, try to reproduce those same conditions.
Check the NDR DD signal line voltage
With the failure duplicated, move to the first voltage check. Turn the vehicle to OFF LOCK, disconnect the CVT drive pulley speed sensor 3P connector, then turn the vehicle back to ON mode. Measure voltage on the NDR DD circuit from connector terminal No. 1, the RED wire, to body ground. You are looking for about 5 V. If you have about 5 V there, continue to the VCC1 check. If you do not have about 5 V, skip ahead to the NDR DD short-to-ground check.
Check VCC1, then sensor ground reference
Next, keep the sensor connector disconnected and the vehicle in ON mode. Check the VCC1 circuit at the CVT drive pulley speed sensor connector terminal No. 3, the PNK wire, to body ground. Again, the expected reading is about 5 V. If that voltage is missing, repair an open in the VCC1 wire between the CVT drive pulley speed sensor and the PCM. If VCC1 is good, check between terminal No. 2, the GRN wire, and terminal No. 3, the PNK wire. This checks the VCC1 and SG1 side of the sensor circuit, and the expected reading is about 5 V. If that reading is present, replace the CVT drive pulley speed sensor. If it is not present, repair an open in the SG1 wire between the CVT drive pulley speed sensor and the PCM.
If NDR DD voltage was missing, check for a short to ground
If the NDR DD circuit did not show about 5 V earlier, turn the vehicle to OFF LOCK, jump the SCS line with the HDS, and disconnect PCM connector C, the 51P connector. With the CVT drive pulley speed sensor connector still disconnected, check continuity from the sensor connector terminal No. 1, the RED wire, to body ground. If there is continuity, repair a short to body ground in the NDR DD wire between the CVT drive pulley speed sensor and the PCM. If there is no continuity, the NDR DD wire is not shorted, so continue to the open-wire check.
Check NDR DD continuity back to the PCM
For the open-wire check, stay in OFF LOCK with the CVT drive pulley speed sensor connector disconnected and PCM connector C, 51P, disconnected. Check continuity from the sensor connector terminal No. 1, the RED wire, to PCM connector C terminal No. 33, also the RED wire. If there is no continuity, repair an open in the NDR DD wire between the CVT drive pulley speed sensor and the PCM. If there is continuity, the NDR DD wire is OK. At that point, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the code is gone after the PCM update, troubleshooting is complete. If P0793 goes away with a substituted PCM, replace the original PCM. Before condemning the original PCM, pause, recheck the earlier diagnostic path, and avoid guessing.
Verification and takeaway
Keep verification separate from the testing. After any wiring repair, sensor replacement, PCM update, or PCM substitution path, verify the repair and confirm the code stays gone under the same kind of operating conditions used to duplicate it. The takeaway is simple: for P0793, prove whether the no-signal condition is intermittent, then work the circuit in order—signal voltage, sensor power, sensor ground reference, short-to-ground, open signal wire, and only then the PCM path. For more diagnostic training, visit stepdiagnostics.com.
Final check
This code often needs an electrical diagnosis of the speed sensor circuit before considering the PCM path.
For more guided automotive diagnostics, visit STEP Diagnostics.
